Continuously variable planetary gear set

Abstract

A continuously variable planetary gear set is described having a generally tubular idler, a plurality of balls distributed radially about the idler, each ball having a tiltable axis about which it rotates, a rotatable input disc positioned adjacent to the balls and in contact with each of the balls, a rotatable output disc positioned adjacent to the balls opposite the input disc and in contact with each of the balls such that each of the balls makes three-point contact with the input disc, the output disc and the idler, and a rotatable cage adapted to maintain the axial and radial position of each of the balls, wherein the axes of the balls are oriented by the axial position of the idler.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 10 / 844,821, filed on May 12, 2004, which claims priority to U.S. Provisional Application No. 60 / 494,376 filed Aug. 11, 2003, U.S. Provisional Application No. 60 / 512,600 filed Oct. 16, 2003, U.S. Provisional Application 60 / 537,938 filed Jan. 21, 2004 and U.S. patent application Ser. No. 10 / 788,736, filed Feb. 26, 2004, and all of these applications are hereby incorporated by reference in their entireties.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The field of the invention relates generally to transmissions, and more particularly the invention relates to continuously variable planetary gear sets that can be used in transmissions as well as other industrial and land, air and water-borne vehicles. [0004] 2. Description of the Related Art [0005] In order to provide a continuously variable transmission, various traction roller transmissions, in which power is transmitted t...

AI Technical Summary

Problems solved by technology

However, the success of these traditional solutions has been limited.

However, the use of iris plates can be very complicated due to the large number of parts that are required to adjust the angular position of the iris plates during shifting of the transmission.

Another difficulty with this transmission is that it has a guide ring that is configured to be predominantly stationary in relation to each of the rollers.

Since the guide ring is stationary, shifting the axis of rotation of each of the traction rollers is difficult.

A key limitation of this design and improvements of this design is the absence of means for generating and adequately controlling the axial force acting as normal contact force to keep the input disc and output disc in sufficient frictional contact against the balls as the speed ratio of the transmission changes.

This excessive axial force lowers efficiency and causes the transmission to fail significantly faster than if the proper amount of force was applied for any particular gear ratio.

The excessive force also makes it more difficult to shift the transmission.

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